The present invention is directed to a device for forming a splice between a moving web from a finishing or terminating roll of material which web is being delivered to a processing machine and an overlapping portion of a new web from a new roll of web material. The device forms the splice between the two portions of the web as the terminating or finishing roll is almost completely used.
The splicing operation such as a lap splicing operation is well known by users of printing, cutting and embossing machines for paper or cardboard. The complete roll and the unwinding roll are placed on a roll support which has arms that can turn around a central axle. The web material unwinding from the roll is delivered at a very high speed and in a continuous mode to a processing machine. In order to avoid any damage to the production, the finishing or terminating roll is replaced during the running of the machine. For this operation, a new roll is brought into rotation so that its circumferential speed is equivalent to the linear speed of the unwinding or moving web delivered by the expiring roll. To bring the new roll to this speed, the device will have means for accelerating which may be either rollers or belts and the means for accelerating will start as soon as the splicing order is given either by an operator or automatically according to the quantity of web remaining on the terminating or finishing roll. The linear speed of both webs is adjusted and the splicing area previously prepared on the new roll is detected. The splicing on the new roll generally comprises pre-glued or self-adhesive faces which allow the gluing of the overlapping portions of the moving web from the finishing roll with a starting portion of the new web of the new roll. As soon as the splicing area is detected and a signal created, a pressure roller over which the moving web from the finishing or terminating roll is passing is pressed against the circumference of the new roll. A transversal cutting device is arranged next to the pressure roll and is actuated as soon as the splicing has been accomplished. The transversal cutting device will cut the moving web which was unwinding from the finishing roll and then moves back to a retracted position. Thus, the web, which is being delivered from the new roll, will necessarily run along the previous path of the web from the finishing roll. Of course, this type of splicing of two rolls will cause a loss at the splicing spot. The dimensions of this loss can vary with regard to the running speed of the web and the time needed by the device to react after receiving the splicing signals. Such a splicing device is described in U.S. Pat. No. 3,195,827, whose disclosure is incorporated by reference thereto.
If the processing machine is a printing press, it might happen that it will use a web, which is partially pre-printed. The roll can be wound with the printed surface or face inside, i.e., turned toward the axle or core of the roll or its printed face turned outside. It also can occur that due to the manufacturing process of the roll, the "good face" of the web can be turned either inside or outside on the wound roll. Thus, the roll must be completely unwindable in one sense or the other according to the request.
A device allowing this kind of splicing is circumstantially described in U.S. Pat. No. 3,622,097. This patent refers to an end-to-end splicing of the web delivered by the finishing or terminating roll and the web of the new roll. This method requires a slightly different processing in the splicing area of the new roll.
Both of the above-mentioned devices have some drawbacks. With the location of the accelerating and pressure elements described in the U.S. Pat. No. 3,195,827, the unwinding sense of the new roll cannot be reversed. The device which is mentioned in the U.S. Pat. No. 3,622,097 allows a change of the rotation direction for the new roll but uses two different elements for this purpose. Moreover, the lap is not pressed directly against the new roll but maintained between these elements. It is also noted that this patent refers to an end-to-end splicing of the web delivered by the finishing or terminating roll which end-to-end splicing is performed with the help of a blade previously inserted in the splicing area prepared on the new roll.